Why there is a problem with the Confirmation Mbox?

There could be multiple reasons causing this issue. You might want to try the below steps and see if it helps.

Try to open the page on another browser and see if the Mbox confirmation page works.

Clear the browser cache and try again to load the page.

Enable mixed content on the browser to avoid any conflict.

See if any javascript is conflicting with the page.

Try the below denug methods:

mboxDebug=x-time to check the response time.

mboxDisable=1 disable mboxes and see if that works.

mboxDebug=x-cookie Modify the cookie.

Also,If you are trying to run a test where the confirmation page is the same as the initial landing page. The conversion trigger is simply a page refresh and is not loading properly and there is an error.

Do the following:

Use mboxUpdate vs. mboxCreate because the offer sometimes pulls the code to the page after it has rendered.

If you are not sure on how to use dynamic mboxes, please refer to the dynamic mboxes help guide link below :